it's about $550-600 new so that's half price. considering what you can get new for $300 (gtx 970/ R9-390 level) it is worth the price and would be a big upgrade from what you are using now.
with that said, if you can wait a bit longer, the new cards coming out should be a bit better for around the same price. AMD is teasing a bit better than that for about the same money and MUCH less power usage but it may be a couple months before they come out. nothing official yet. nvidia will have something in that range as well but likely won't be out until the end of the year or thereabouts.
personally, i'd go for it, but i can handle not having the latest and greatest. just be sure you power supply can handle it, as it is power hungry. that...